Evidence suggests that an increased incidence of cleft palate may be associated with HLA-A2, a major histocompatibility complex antigen. If this is true then HLA antigens can be used as genetic markers for increased susceptibility to cleft lip and/or palate. The proposed studies have been designed to confirm the HLA/cleft palate association. Cooperating institutions throughout the Los Angeles Metropolitan area will provide subjects to be HLA typed. About 1,100 patients will be available. All HLA typing of experimental and control populations will be done by the UCLA HLA typing facility directed by Dr. P.I. Terasaki. A sample of blood containing live cells and a sample of serum from each patient will be preserved in liquid nitrogen for future use. The identification of genetic markers for cleft lip and/or palate susceptibility will lead to the development of procedures to reduce the incidence of these craniofacial anomalies.